Monolayer MoSi2N4-x As Promising Electrocatalyst for Hydrogen Evolution Reaction: A DFT Prediction

The density functional theory (DFT) calculations have been performed to investigate the catalytic properties of monolayer MoSi 2 N 4 for hydrogen evolution reaction (HER). The DFT results show that similar to the majority of other two-dimensional (2D) materials, the pristine MoSi 2 N 4 is inert for HER due to its weak affinity toward hydrogen, while monolayer MoSi 2 N 4- x ( x = 0-0.25) exhibits the highly desirable HER catalytic activities by introducing surface nitrogen vacancy (NV). The predicted HER overpotential (0-60 mV) of monolayer MoSi 2 N 4- x is lower than that (90 mV) of noble metal Pt, when the concentration of surface NV is lower than 5.6%. Electronic structure calculations show that the spin-polarized states appear around the Fermi level after introducing surface NV, thus making the surface NV on 2D MoSi 2 N 4 a quite suitable site for HER. Moreover, the HER activity of MoSi 2 N 4- x is highly dependent on the surface NV concentration, which can be further related to the center of Si-3p band. Our results demonstrate that the newly discovered 2D MoSi 2 N 4 can be served as a promising electrocatalyst for HER via appropriate defect engineering. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.